Projection Pushdown bug in 11.2.0.3

There’s a bug in 11.2.0.3 related to projection pushdown that seems to be influenced by the setting of STATISTICS_LEVEL.

Having taken the time to distill a test case from a real world issue (commenting out columns and logic and bringing view definitions inline etc – original query had no reference to DUAL), turns out it’s very simple to reproduce:

Unfortunately, if you’re turning projection pushdown off, then that must critically change the plan of the statement you’re looking at.

Any thoughts that you might use the column projection information of DBMS_XPLAN to help diagnose the bug are scuppered by the fact that this is obviously raised at parse time.

What is particularly disappointing is that we found this on Day 1 of testing an application against 11.2.0.3, an application which we’ve previously tested extensively on 11.2.0.2 and were considering 11.2.0.3 rather than request individual backports for a couple of specific, unrelated bugs that we’ve yet to address on 11.2.0.2.

And this despite the fact that bug 7041059 is not believed to affect 11.2 plus the fact that this was not an issue in 11.2.0.2 and it is an issue in 11.2.0.3 and despite this not involving user-defined operators.